1: remove all orings and the bumper from the bolt . Tape up the 2 #12 oring grooves so they are protected from nicks and scratches during drilling. most any tape will work, your just trying to cover the vital sealing areas from damage.

2:take the G drill bit and line it up with the bolt guide so there is a .050-.070" gap between the taper tip of the drill bit and the tapered part of the bolt guide(the tapered part of the bolt guide is right in front of the back #12 oring groove. Mark the drill bit with a sharpe where it is flush with the back of the bolt guide. This is how deep you want to drill with the G bit.

3:take the L drill bit and mark it the same way as the G bit except this time line the tip of the drill bits taper up with the back wall of the back #12 oring groove. mark the bit with a sharpe where it is flush with the back.

4:now take the Q drill bit and line the tip of it up so that there is a .050-.070" gap between it and the rear tapered part of the bolt guide. mark with shape where flush.

5: mount the guide in your drill press/ lathe/ mill and center the 3/16" allen socket on the back of the guide with the chuck of your machine. Drill first with the G bit, then the L drill bit, and finally the Q drill bit.

6:now take the 3/8-24 tap and tap the hole in the back of the bolt guide until the tap stops or bottoms out

7:Next mark 3 evenly space dots around where the rear #12 oring grooves taper meets the 1/4" shaft between the 2 #12 oring grooves. use the dremel and the #31 drill bit(or 1/8" bit) to drill the 3 holes. you want to hold the dremel at an angle so that the taper tip of the drill bit is parallel to both the 1/4" stem and the rear #12 oring groove's taper. drill until you feel the bit break through into the hollowed out center section of the guide.

8:remove the tape and clean the bolt guide with soap and water extensively

9:Now take one of the 3/8-24 set screws, apply blue or red locktite and screw in until the back of the setscrew just passes the 3 holes in the rear of the guide. *OPTIONAL- you can grind down the front and back of the setscrew before placing it in the bolt guide so that it is as low profile as possible. this will allow for the most volume possible.

10:Next take the remaining 3/8-24 setscrew and drill it out from the non allen socket side with the #14 drill bit. It helps to hold the setscrew if you thread it into a 3/8-24 nut and mount the nut in the vise.

11:Finally blue or red locktite the drilled setscrew flush with the back of the bolt guide and allow both setscrews 24 hours to dry. re-install the orings and bumper and your done.

I should mention that this mod is really 2 mods in 1 in the fact that it fixes stripped allen sockets in the back of bolt guides as well as adding more shot volume. the new set screw is the same allen key size as the stock bolt guide and the steel or ss construction guarantees it will never strip again. I will post a revised and shortened walkthrough on just fixing stripped bolt guide hex sockets for those who dont want/need the low pressure part of the mod.

As long as the first set screw that seals the chamber is deep enough it should work just fine. The second set screw is drilled through to vent the chamber like normal. I assumed there was a bit of space between the 2 set screws once they are locktited into place.

As long as the first set screw that seals the chamber is deep enough it should work just fine. The second set screw is drilled through to vent the chamber like normal. I assumed there was a bit of space between the 2 set screws once they are locktited into place.

this./\

the first setscrew is solid and seals the new air chamber inside the bolt guide. it is place directly past the 3 holes in the bolt guide so that those holes vent and function as normal. the second set screw is flush with the back and is hollow to allow air to flow through. the gap between the 2 setscrews is about 1/2".

I'll see if I can find a cad drawing of a bolt guide and edit it to better show the final product.

From what I've gotten out of the various threads, the Eigenbolt actually likes more volume than less, at least up to a certain point. The recock assist slots in front of the sail need residual pressure from the dump chamber to work, so an SFT can would be more beneficial than an HE can.

On Topic - This is an awesome guide to modding the bolt guide ccluff, thanks for putting it together.

I did this a while back along with the adjustable guide mod and I just used a smaller drill bit and you wouldn't have to use the second set screw. I didn't drill out the Allen head part of the bolt guide. This version would definately allow for more volume thanine though. Good job as usual ccluff